Document verification system

ABSTRACT

The present invention relates to a computer-implemented method, and associated apparatus, for printed document verification. A document to be printed will have related content data, imposition data, and finishing data, wherein the imposition data describes at least one imposition signature for the document and the finishing data describes the application of one or more finishing operations to be performed in order to produce the printed document. This data is obtained using an input device and is passed to a representation system that generates an electronic output representation of the document to be printed and finished, in accordance with the said content, imposition and finishing data. An operator can then inspect this electronic representation to check for errors that might arise.

This invention relates to methods and apparatus for verifying a printeddocument, in particular through previewing the document to be printed.

The concept of imposition is well known within the printing industry andconcerns the arrangement of pages of a document on a sheet of paper orother print medium so that when folded in the correct manner they willcreate a finished publication or part of a publication. This arrangementof pages is referred to as an imposition layout. To aid the printingprocess a variety of printers' marks are often applied to the impositionlayout to produce what is known as an imposition signature.

Commonly, the document to be published is received in a page descriptionlanguage (PDL) file wherein the pages of the document are arranged inreader order suitable for display on a standard computer system.

Most pre-press workflow systems have the ability to combine the contentof a document stored in the PDL file with an imposition signature andthen to create an image on the printing plates used in the printingpress to print the document. The printed output of an impositionsignature may contain one or more imposition sheets. The printing mediumis usually printed on both the front surface and back surface of thesheet.

Typically pre-press workflow packages are able to display, on screen, arepresentation of the printed result. This view is most commonly used todetect problems prior to printing. The printed result is typically madeup of several separations, wherein each separation is associated with adifferent printing ink colour. The view will typically allow the user toselect, in any combination, the separations to view so that printmanufacturing details can be explored (such as overprint, trapping etc).Such viewer applications typically allow different combinations ofseparations to be viewed together, the zoom factor to be altered, andthe on-screen colours to be adjusted along with other standard viewertype features. A pre-press operator will also be able to print out afacsimile (or proof) of the imposition sheet for verification.

After the printing of an imposition signature, the job of creating apublication requires a number of additional steps (‘finishing’). Eachfinishing step has to be correct and consistent with the others. Forexample, the creation of a typical commercial printing publicationconsists of several steps including: printing, cutting, stacking andfolding, binding and trimming the sheets. These steps are carried out bya variety of known printing machinery such as the Muller Martini ValoreSaddle Stitcher and the Apollo Stacker

A typical printing run for a publication may consist of a long sequenceof individual steps. The sequence of steps that must be managedautomatically is becoming more complex as the printing line becomesincreasingly automated and publishing clients demand more flexibility atlower costs. For example, several different publications are oftencombined on one sheet (ganged) in order to save paper and eachpublication can further contain several different folded sheets. Eachsheet can further be printed on different media. When inspecting theimposition signature the pre-press operator typically has to rely ontheir experience to notice when errors may occur. Whilst this processpresents difficulties for even the most skilled operator, with theintroduction of ‘on-demand’ publishing, managing this process anddetecting errors becomes near impossible. In these situations machinery,personnel, and even locations may change at a moments notice and oftenthe operator will require several dummy runs through the printing lineto finalise the imposition layout and finishing details. This, ofcourse, adds time delays and increases the production costs of thepublication.

According to a first aspect of the present invention, there is provideda computer implemented method of printed document verificationcomprising obtaining content data relating to the content of a documentto be printed; obtaining imposition data describing at least oneimposition signature for the document; obtaining finishing datadescribing the application of one or more finishing operations to beperformed in order to produce the printed document; and generating anelectronic output representation of the document printed and finished inaccordance with the said content, imposition and finishing data.

A new approach to the error checking of impositions is proposed. Themain purpose of the new system is to allow imposition signature, foldingand finishing errors to be detected before a publication is committed toa substrate. It also aids in the diagnosis and correction of sucherrors. Such a system is required for checking the work of an automatedimposition creation system.

Hence, an operator is able to inspect the output representation of theprinted document to check that no errors are present without physicallyproducing the printed document. The representation system generates arange of views, by reading imposition and finishing parameters. In allviews, currently displayed items can be rotated in any direction andindividual pages can turned in both ways. The system is capable ofsimulating both publication composition, the visual assembly of sheetsthrough the process of sheet stacking, cutting, folding and binding, andpublication decomposition, the reverse process, in a three-dimensionalgraphical environment. Publications can thus be composed from theirparts or decomposed from the bound work to allow for easy checking.

According to a second aspect of the present invention, there is provideda printed document verification system comprising an input deviceadapted to obtain content data, relating to the content of the printeddocument, imposition data, describing at least one imposition signaturefor the document, and finishing data, describing the application of oneor more finishing operations in order to produce the printed document; arepresentation system comprising a processor adapted to generate anelectronic output representation of the printed document in accordancewith the said content, imposition and finishing data; and an outputdevice adapted to output said output representation.

An embodiment of the invention will now be described with reference tothe accompanying drawings, in which:

FIG. 1 shows a system of verifying printed documents according to afirst embodiment of the current invention;

FIG. 2 shows a flowchart demonstrating a typical set of finishingoperations to be performed on a representation;

FIG. 3 shows a flowchart demonstrating a method of producing printeddocument representations according to a first embodiment of the currentinvention;

FIG. 4 shows a system of verifying printed documents according to asecond embodiment of the current invention;

FIG. 5 shows the imposition signature of an inner section of a documentto be published;

FIG. 6 shows the imposition signature of a cover section of a documentto be published;

FIG. 7 shows a folding operation;

FIG. 8 shows a method of gathering multiple folded sheets of apublication;

FIG. 9 shows a method of collecting multiple folded sheets of apublication;

FIG. 10 illustrates four binding examples;

FIG. 11 shows a method of checking the order of multiple folded sheetswhen bound.

With reference to FIG. 1, an apparatus used to implement the currentinvention will now be described. A pre-press environment comprises animposition system 116, a management information system (MIS) 102connected to a database 117, and a representation system 108. Both theimposition system 116 and the representation system 108 comprise aprocessor, a hard disk, a display device connected to a graphicsprocessor and input/output devices, such as a mouse, a tablet, akeyboard, a touch-screen or a wireless indicator.

The pre-press environment will be used in conjunction with a printingpress 107 and finishing devices 118. This communication can be achievedusing network communications (LAN/WAN/Internet), or through physicallocality. The printing press 107 will comprise one or more printingapparatus 118 forming a printing or production line. Typically, eachprinting apparatus will be used for a different finishing operation.

Information relating to the operation of the printing press 107 will bemanaged by the MIS 102, which typically comprises the database 117 anddatabase management software. It is used by the management of theprinting press 107 to aid in the operation of the company, and contains,for example, optimised printing schedules, media stock information,costing information and information about the finishing devices 118,including machine availability and appropriate operating parameters.

The imposition system 116 is adapted to produce an imposition signature113 on receipt of content information concerning a document to beprinted. This content information is stored electronically in a file101, such as in XML format. The resulting imposition signature can bestored in a printing information (PI) file 105, for example a filesystem comprising PDF or TIFF representations of the content pages andan XML file containing data specifying a set of processing parameters103. The PI file will contain the sequence that the finishing operationswill be applied.

The imposition system 116 is further adapted to receive processingparameters 103 obtained from the MIS. These parameters can be used inthe production of the imposition signature. The MIS may further compriseone or more optimisation algorithms that take a description of therequired publication (delivered as content data in file 101), thecompany database 117 and information from the operator as inputs anddecide on the appropriate finishing devices 118 to use for thepublication.

For example, the content data could contain 32 pages of A4 size and theoperator could select ‘glossy’ as a media type. An optimisationalgorithm 115 would then look up all glossy media in stock in thecompany database, and calculate which particular glossy media wouldprovide the cheapest publication. The number of pages, set within thecontent data, would then allow the optimisation algorithm to choose themedia size, the number of sheets and the number of pages per sheet. Theoptimisation algorithm 115 would then look up all printing apparatuspresent in the company database 117 designed to print and finish theparticular size and type of the chosen media, and filter the results toselect free machines. Output information in the form of processingparameters 103 would then be provided to the imposition system 116 tocreate the imposition signature 113.

The representation system 108 is adapted to produce electronic outputrepresentations 109 of a variety of finishing operations. It is furtheradapted to receive a printing information (PI) file 105 as an input.This file contains data comprising the imposition signature, completewith imposition layout and printers' marks, together with details of allthe finishing operations to be applied to the printed imposition sheetthat will be created from the imposition signature. This data thusprovides all the parameters required to build virtual models of theprinted document at various stages. Often, the data will containmultiple imposition signatures relating to different sections.

Instruction sets defining a three-dimensional modelling software suiteare stored upon the hard disk of the representation system 108. Theprocessor then executes these instruction sets. This suite may beadapted from those known in the art, such as adapted computer aideddesign (CAD) packages or adapted modelling software suites, such asLightwave modeller or Rhinoceros 3D. Alternatively, the software can bebuilt using known object-orientated methods and libraries. For example,a geometric modelling kernel can be built around a number of knownprogramming modules, which are distributed with their own applicationprogramming interfaces (APIs). These modules allow the development ofparametric feature-based modelling environments and freeform surfacemodelling systems, which can be interfaced into standard pre-presssystems.

The representation models described herein can be implemented using anymethod known in the art, for example, using constructive solid geometryor polygonal modelling, or through the use of implicit surfaces orB-splines. Further known methods and systems can be used to generate theanimations that demonstrate the finishing steps applied to createsubsequent representations. Furthermore, the method of generating arepresentation can be performed by bespoke hardware, such as a dedicatedgraphics integrated circuit connected to input/output devices or anembedded system with dedicated modelling capabilities. Alternatively, itcan be performed by implementing, on a general purpose processor,instructions stored upon a computer read-able medium ortransmission-type medium.

A particular three-dimensional representation is built by providing aninterface between the received PI file 105 data and the parametricmodeller forming part of the representation system 108. Specificfunctions will extract the relevant geometric data from the impositionsignature and use this geometric data in the creation ofthree-dimensional objects. For example, the PI file will specify themedia size and media type to be used to create each imposition sheet.This information can be used to look-up the required height, width anddepth parameters for a three-dimensional model of a cuboid. A cuboid canthen be generated with the appropriate dimensions. The content data,containing the graphics and text to be printed, can then be rendered asa surface and applied to the cuboid, generating a three-dimensionalmodel of a printed imposition sheet.

The representation system 108 is further adapted to apply virtualfinishing operations to the generated three-dimensional model. Withinthe printing press 107, a real printed imposition sheet will bemanipulated by a series of finishing devices 118. Each virtual finishingoperation thus consists of manipulating the three-dimensional modelbased on the real life manipulations applied by each finishing device.The virtual finishing operation may consist of modelling the process ofcreasing, cutting, embossing, gluing, perforating, strapping, stacking,folding, collecting, ganging, gathering, binding, trimming or any otheroperation known in the art of publishing.

The finishing data in the PI file 105 contains the details of eachfinishing operation, together with a corresponding set of finishingdevice references. As previously stated this may be stored in XMLformat. The representation system 108 will parse the finishing data toextract the list of finishing operations to be applied to a virtualimposition sheet. For each operation on the list, the finishing devicereference is extracted from the finishing data, together with parametersspecifically related to the selected finishing operation. For ease ofmanipulation, the finishing parameters can be designed to be finishingdevice independent.

For example, a fold may be performed on a Horizon AFC-546AKT. This foldmay be referenced through a fold catalogue entry. Entries in thecatalogue may either be industry standard entries or may be userdefined. The entry may take a form such as “F 8-4”, which is translatedas “fold an 8 page imposition layout with fold option 4”. Fold option 4is then detailed in the catalogue. Thus the geometric manipulationsassociated with this fold can be extracted from the catalogue andmodelled within the representation system modelling environment. Themanipulations can be coded within a bespoke object or function withinthe representation system. For example, a given fold could berepresented within the environment as a method that performs a clockwiserotation of 180 degrees of a sub-section of virtual imposition sheetobject about a line in the centre of the sheet object. These methodstake the dimensions of the particular imposition sheet being manipulatedas input data.

If the details of the finishing operation are dependent on the finishingdevice to perform the operation, each finishing device can be modelledas an object, wherein the geometric manipulations associated with afinishing operation are provided as methods of this object. Thus theabove fold could be initiated by a call line such as“output_object=machineX.fold(input_object, P8, F4)”, which will return ahandle to a new three-dimensional object or group of objectsrepresenting the result of the finishing operation, such as those shownin group 111. This output object is then displayed on screen through theobject methods provided by the modelling libraries.

If the details of the finishing operation are independent of thefinishing device, each finishing operation can be modelled as an object,which has associated methods that take an existing three-dimensionalmodel and finishing parameters as input data and produce an outputobject representative of the geometrical manipulations involved in thefinishing operations. The content data can either be already containedwithin the object models or added, with the appropriate deformations, tothe page slots on a manipulated imposition sheet.

The final output of the representation system 108 is a three-dimensionalproof 120 of the document to be published. This is a model object, whichis linked to a group of intermediate processed (or ‘finishingstep’-‘FS’) objects 111.

An example of the method of the current invention will now be presentedwith reference to FIG. 2 and FIG. 3. It is to be noted that this exampleshould not be limiting and can be applied to other forms of publisheddocuments.

A document to be published consists of a 32-page inner and a 4-pagecover. An operator of a pre-press computer system will receive thisdocument to be published, S300. This document may be representedelectronically in a common PDL file, such as a PDF, postscript or TIFFor, alternately, supplied physically and converted to electronic formthrough input methods known in the art, such as raster scanning.Typically, the document is provided by a design team or advertisingagency that is responsible for the creative content of the publication.The document will have pages of a certain size and usually contain amixture of images and text.

The operator will then inspect the document and make a series ofproduction decisions, S301, directed towards the commercial printing ofa document. These decisions will often be independent from the artisticconsiderations, and cover issues related to cost and productionefficiency. Examples of the decisions that need to be made are: how manycopies are to be produced; the production schedule; what media is to beused; what is the specifications of the selected media; is there to beone or more sections of a different media; how many colours are to beused; whether any spot colours are required; what printing apparatus isavailable; how many sheets are to be used; and what finishing steps arerequired. These examples are non-exhaustive and will depend onparticular circumstances.

After these decisions have been made an imposition layout will then beproduced; either manually, relying on the operator's skill andexperience, or automatically, using imposition systems known to the art.To automatically produce an imposition layout the operator needsinformation derived from the original PDL file and the followinginformation: the size of the media, e.g. B1, A1 or any of the standardpaper sizes, the number of pages to place on the media sheet, e.g. 8 or16, and the printing apparatus and finishing devices available. Theinformation retrieved from the PDL file contains the number of pages andthe different sections of the publication, e.g. cover and inner.

The imposition system can be adapted to obtain any of this informationfrom the MIS, or from algorithms that use the MIS information as inputdata. For example, the number of pages and content type could beretrieved from the PDL file and input to an optimisation algorithm thatinspects the media stock of the press, performs cost calculations andthen matches the content type with a media type in stock. Availableprinting apparatus suitable for the media type are then selected, andthe algorithm determines parameters based upon these apparatus, such asnumber of pages per sheet, folding and stacking types etc.

Alternatively, the current invention provides a wizard or graphical userinterface, which directs the operator through the decisions to be made.This wizard may limit production options based on information from theMIS. Whatever method is used, the end result is an imposition layout anda collection of data ('finishing data') related to the finishingoperations required to produce the publication.

The operator will then add a series of printer's marks to the impositionlayout to produce an imposition signature. As the cover and inner of thedocument are to be printed on different media, different impositionsignatures will be required for each section. The imposition signaturefor the inner is shown in FIG. 5 and the imposition signature for thecover is shown in FIG. 6.

The printers' marks 502, 602 may include colour bars, cutting lines,collation markers, orientation markers, fold lines, register marks orany other marks known to the art. These marks can be assignedautomatically or manually. If added automatically they may have beenpredetermined by the options selected in the wizard or automaticallycalculated by the said MIS optimisation algorithms. For example, foldlines and orientation markers will depend on the imposition layout andthe fold type used.

The imposition signature will then be combined with the documentcontent, stored in the PDL file, by placing the text and graphics ofeach page in the PDL file, into the page slots in a graphicalrepresentation of the imposition layout. The imposition signature isthen stored alongside the finishing data in a printing information (PI)file. This is displayed in step S302 of FIG. 3. This file can then beforwarded to the printing press for the actual production of thepublication or viewed on a standard computer system with appropriatesoftware.

Before sending the PI file to the printing press the file will be loadedinto the representation system in order to produce a representation ofthe document at each stage of the finishing process. Theserepresentations will typically be inspected by a pre-press operator butcould be forwarded to any of the printing staff.

After the PI file is loaded or imported into the representation system108, a first representation is created. This representation displays theimposition signature 113 with the document content and printers' marksin place as a virtual imposition sheet, S200 and S303. Thisrepresentation can be displayed visually within a three dimensionalvirtual world on the representation system using the techniquespreviously described. In the current example, the virtual impositionsheet is generated as a three-dimensional cuboid but in practice couldbe approximated by a two-dimensional plane. The operator will then viewthis representation through a standard display device, such as a LCDmonitor or CRT display device.

The virtual imposition sheets can then be seen and manipulated withinthis three dimensional world. For example, each virtual imposition sheetcan be generated using the three-dimensional model previously describedand rotated so as to expose the rear-side for basic rear side checking,such as checking page content or alignment. Alternatively, the operatorwill be able to lift and turn the sheet edge to check the rear-side ofthe virtual imposition sheet. Some or all of the sheets for some or allof the signatures can be viewed. The printers' marks can further beswitched on and off in the view area to aid legibility.

Now the finishing operations can be applied to the imposition sheetmodel, S304. Often in commercial printing, pages for differentpublications will be included on the same printed imposition sheet. Inthis case the printed sheet will need to be cut by cutting apparatus toseparate the publications. The relevant cuts will be marked by theappropriate printers marks on the virtual imposition sheet. If a cut isrequired the representation system will enable the operator to make avirtual cut, S201, in the virtual imposition sheet, representative ofthe cutting operation to be performed by the cutting apparatus.

For example, an icon or pointer representing pair of scissors may beavailable to the operator, which enable the operator to make ‘cuts’ inthe virtual imposition sheet. This icon or pointer can then bemanipulated by input means known in the art, such as computer mice,tablets, keyboards, or known virtual reality interface equipment. Therepresentation system will only allow a virtual cut to be made when itdetects an input signal from the input means within a two or threedimensional range surrounding the cut lines dictated by the impositionsignature. When this input signal occurs it will initiate objectsmethods that generate a virtual cut, e.g.“cut_object_group=machineY.cut(input_object, cut_line)”, where the“cut_object_group” is the group of parametric objects that result fromthe virtual cut. If the cut separates one imposition sheet into two, twonew three-dimensional sheets will be produced with geometric dimensionscalculated by factoring in the line or plane of the cut. The result ofthis finishing operation can now be represented on screen S305.

Subsequently, the representation system 108 checks the list of finishingoperations extracted from the finishing data, S306. As the inner of thedocument to be printed is constructed from two virtual impositionsheets; an animated view of sheet stacking will be available, S202. Thisanimation will stack the two virtual imposition sheets in a manneridentical to the designated stacking apparatus. This will typicallyinvolve aligning two or more three-dimensional objects with a common setof reference axes and extracting the nature of the alignment from thefinishing data. This may be initiated by a command such as“machineA.stack(input_object_group, stacking_parameters)”, wherein thegroup of objects to be stacked is provided as an input. The stackingparameters may comprise a two-dimensional offset from a two-dimensionalupper surface of a first object, for a two-dimensional lower surface ofa second object, (present in input_object_group), together with surfacelabels.

Thus if there is any misalignment introduced during this operation itwill be visible to the operator. It is possible to further manipulatethe stacked sheets in three-dimensions through rotation, opening pages,zooming or general translation, to check for any alignment and page flowerrors.

Following stacking, a representation of each folded imposition sheet,sheet-stack, or cut-sheet is generated. An example of a foldrepresentation is given in FIG. 7 and the folding process may beinitiated by a command such as that cited previously. To enable theoperator to clearly follow the logical steps that generate the finishedfolded sheet from a set of stacked sheet objects, an animation of thesheet being folded according to the required fold catalogue entry ispresented, S203. As previously described, the representation systemcontains a library of animations and fold configurations according toeach entry in the fold catalogue. The fold catalogue code is passed tothe representation system 108 within the finishing data. The operatorcan thus manipulate the folded object and check that the folds are asrequired for each section. Furthermore, the folding animation can bereplayed if needed.

In modern publishing the number of available folding operations can belarge with high levels of complexity. For example, modern newspaperprinting often involves offsetting the centre fold of a document, toprovide a lip on an outer sheet to enable advertising pamphlets ormagazines to be mechanically inserted. This offset can introducealignment errors if not taken into account. When denoting, the operatoridentifies the appropriate page slots in the imposition layout. Thus thecurrent system allows an operator to check the result of multiplecombinations of features, which may present non-obvious resultanterrors.

If several imposition sheets have been stacked before folding, thevirtual fold operation will be performed on this stack of sheet objects.This can be implemented by treating the stack of sheet objects as asingle object and applying a fold method to this single object.

The representation system 108 provides a variety of options forinitiating the fold animation: either the operator can select anauto-fold icon which will fold the sheet in the appropriate manner andproduce the folded object that can be rotated as willed; or the operatorcan step through each step of the fold operation ‘manually’ on screen.The latter option comprises using an icon or pointer, as with thevirtual scissors, which can be shown to ‘grab’ a side of the sheet to befolded, i.e. the edge of a plane subsection of the sheet that is to berotated about a fold line, before ‘dragging’ that side about arepresentation of the fold line, i.e. rotating the plane subsection, inorder to display a representation of the folding operation. The locationof the fold lines to be displayed can be present in the impositionsignature as printers' marks or added by the representation system 108based on the fold catalogue entry. Visual cues can also be provided toaid with the ‘manual’ folding, such as highlighting the appropriate foldlines a particular colour or adding arrows highlighting the sides of thesheet that can be folded.

If the sheet requires cutting or stacking before the fold operation thenthis representation must be displayed before the fold animation isinitiated. This corresponds to the fact that the representation system108 will only allow virtual operations identical to, and in the sameprescribed order as, those specified in the imposition signature andfinishing data. The prescribed order is set by the finishing processesrequired for a particular publication and may vary for differentpublications. In a similar manner, once a sheet has been folded, it canonly be manipulated in its folded form. Thus, again, only manipulationspossible in the real world can be performed. For example, with arepresentation similar to FIG. 7, it would only be possible to open theunfolded corner of the folded sheet, and thus it would not be possibleto view the inside of the top left corner. To return to a previousrepresentation the folded object must be unfolded.

Alternatively, in order to allow the inside of folded sheets to beinspected, the representation system 108 provides a temporary “auto-cut”command. It can be implemented through a method related to the currentrepresentation object, for example“cut_object=current_object.cut(cut_line)”. This will apply a trimfinishing operation, removing a portion of the current three-dimensionalmodel object. This operation is representative of a trim operationavailable on existing machinery, to the folded publication. The operatoris then not restricted by the fold and can leaf through pages to verifypage order and alignment. The operation can be undone by a command suchas “current_object=cut_objectuncut( )”, initiated by clicking on a givenicon within the software suite GUI.

After folding, if there are multiple folded sheets, these multiplesheets will be collected or assembled ready for binding, S204. Possiblecollection operations are shown in FIG. 8 (‘Gathering’) and FIG. 9(‘Collecting’). Such operations may be combined to give more complexassembled publications.

The representation system 108 provides a “select all” and “apply to all”command option that enables the set of finishing operations to beapplied to all sheet objects that form the publication. This can beimplemented by having an object family or hierarchy. A publicationdocument object 120 will contain a series of finishing step objects,represented by group 111 in FIG. 1, and each finishing step object willcontain a number of sub-section objects 112. These sub-sections may bepublication sections, such as groups of pages that make up differentinner and cover sections or groups of pages printed on different media,and/or multiple groups of pages that require different finishingoperations, such as some pages may need laminating and some may needembossing. For example, in our example if the two imposition sheets werefolded separately then collected, if the operator has stepped throughthe finishing operations for the first sheet object, they canautomatically apply the same steps to the second sheet object. Thus thetwo sheets will be ready for collection.

The representation system 108 reads the type of collecting to beperformed from the finishing data and applies the collecting operationto a set of folded sheet objects. This is implemented by mating certainlines or surfaces on each folded sheet object. For example, in FIG. 8,the surfaces of centre folded sheet object 801 will be mated with thesurfaces of folded sheet objects 802 and 803 at the points where eacharrow passes through the surface 804. These points will be specified inthe finishing data, either in association with given printers' marks orimplicit when given the form of collection and appropriate finishingdevice. For example, the command may resemble“gathered_object=machineG.gather(input_object_group)”.

If the sheets have been gathered, any collation marks 1101 can be seenso as to detect missing sections, as shown in FIG. 11. The collectioncan also be rotated in three-dimensions to check the procedure iserror-free. It is also useful at this stage to leaf through the pages ofthe publication to check the visibility of any printers' marks. The“auto-cut” feature can be used if the document is not yet trimmed. Forexample, a printers' mark can be designed to reside along a fold line,yet the actual folding may leave part of the mark visible, resulting inan unsightly feature on the printed document. This can be spotted usingthe representation system 108 and the printers' marks subsequentlyrealigned.

It is at this stage that any other sections of the publication can bedragged into the three dimensional space, for example the cover sectionobject can be imported into the space containing the collected innersection objects. A list of all objects related to a publication orfinishing operation is stored in a window available to the GUI. The twosections can then be manipulated to check sizes and the fit for binding,for example the inner can be inserted into the cover.

The representation is then ready to be bound, S205. Examples of possiblebinding options are shown in FIG. 10. The representation system 108 willretrieve the appropriate binding intent from the finishing data anddisplay an animation representative of the physical binding operation.For example, if ‘saddle stitch’ binding is required then the innersection object will be inserted into the cover object, by applying theappropriate geometric transformation, e.g. surface mating, to the objectgroup, and then the cover will be fixed by a chosen method, e.g. staple.The fixing of sections can be represented as the application ofgeometric constraints to a staple object with respect to the inner andcover object, e.g. “inner_object_point_location(x, y,z)=outer_object_point_location(x, y, z)”. Operator manipulation is thenprimarily applied to the family object containing both cover and inner.If the publication is to be ‘perfect bound’ the edge of the cover andinner is ‘ground’, i.e. in the representation a portion of both objectswill be removed, and then glued, i.e. the movement of a plane model ofeach page will be restrained along the ‘glued’ edge.

Finally, a trimming operation will be applied to the boundrepresentation, S206. This can be simply achieved by removing a portionof the bound object according to the trim marks and finishing data. Thiscan allow the operator to check the ‘bleed’ parameters provided in thefinishing data, i.e. whether the graphics of a page extend slightlybeyond the trim marks of the page to prevent a white line forming if theare small errors in the alignment of the trimming apparatus.

The remaining representation is now a three-dimensional proof 120 of thepublication that will be produced using the imposition signature,content data and finishing data initially specified. Thus therepresentation can be further checked for page orientation andalignment, visibility of printers' marks and page flow. In comparison toprior art three-dimensional proofs, which were generated using only thereader order provide in the original content data, the three-dimensionalrepresentation created by the current system will display any featuresintroduced by production of the document. For example, if a fold wasincorrectly set, or a different stacking machine was used, this wouldall be represented in the final proof, whereas this information isignored by the prior art.

The accuracy of this representation then provides numerous advantagesfor the pre-press operator. The operator is able to spot any errors or,visual aberrations present in the finished document and alter thembefore any document or trial copy of a document is made. This savesmoney and time, in the form of machine costs, media costs, and manualimplementation of ‘dummy’ proofs. As the representation will only modelthe printing and finishing operations dictated by the operator, thecolours and alignment of text and graphics will be entirelyrepresentative of the finished document, rather than a copy of theoriginal PDL file. Real-life textures representative of the mediaselected and a variety of lighting options are available to enhance thequality of the representation. Known rendering modules or the featuresof the aforementioned modelling suites can provide these effects. Thus a‘contract proof’, which is normally printed before the printing line isstarted to check colour, graphics and text, is not needed.

The final three-dimensional proof can then be sent to the originaldesign team, or the organisation or individual who commissioned thework, to allow customer verification of the finished article before anyphysical copy is produced. The representations of each finishing step111 can also be included in the 3D proof output.

The representation system 108 also provides functionality that allowsvirtual imposition sheets, which can normally be modelled astwo-dimensional planes, to have depth. This is implemented by providinga three-dimensional object with height, width and depth parameters basedon the media onto which the imposition signature is to be printed. Thisobject can be provided with attributes and methods, using theobject-orientated paradigm, which allow a fold to take into account thedepth of the media. Thus aberrations such as “creep”, the slight butcumulative offset of the edges of inserted folder sheets, and“bottling”, the skewing of pages due to paper thickness as it is folded,can be viewed in the representation, by extending the accuracy of thethree-dimensional models. Moreover, if any corrective compensation hasbeen added to the imposition signatures to compensate for the aboveaberrations, the operator can verify their success or any possible sideeffects.

The sheet object can also be further extended to provide stress andstrain coefficients to accurately model the deformation of the mediaunder the forces applied by the printing apparatus. In addition theeffect of paper grain direction can also be represented.

In a second embodiment of the current invention the imposition creationsystem and the representation system are combined into a singlepre-press system 408. This system is shown in FIG. 4.

An operator will receive the content of the document to be printed in aPDL file 101, or similar, as before, and then proceed to create a newprinting job in the combined pre-press system. On creation of a new jobthe operator will be presented with a wizard in the form of a graphicaluser interface. This will guide the operator through the printing andfinishing parameters 103 that need to be entered, and, as before, may becomplemented by optimised decisions based on MIS data.

After the required data has been gathered, an imposition signature willbe automatically produced for each section as required and these will bedisplayed as imposition sheets as previously described. The variousfinishing steps can then be stepped through as before.

In this embodiment, however, the operator can dynamically change thefinishing steps, for example the imposition, folding and bindingparameters 103, if they detect an error or an element of therepresentation they are not happy with. After changing the requiredparameter the three-dimensional representations are regenerated. Thisprocess can occur automatically after each edit or can be initiated bythe operator by clicking on a command button after a series of edits.

For example, fold and cut lines can be moved using a ‘drag and drop’method and the representation will be regenerated according to this newfinishing data. Tool bars, and other graphical user interfaces, areprovided to enter new or edited finishing parameters 103. For example,the media type may need to be dynamically changed due to lack of stock,and the effects of using a different media type evaluated. The operatorcan then select the new media from the appropriate drop-down menu andthe parameters of the representation models will be changed accordingly.Thus, the operator can see whether they need to change ‘bleed’ or‘bottling’ parameters 103. In addition if such a change has been madeand the imposition has been automatically regenerated by the combinedsystem 408 then the operator can check that the new imposition iscorrect.

As well as the ability to edit any of the finishing data and readjustthe representations accordingly, the combined system provides theability for the operator to dynamically alter the imposition layout 113or the location of a particular printers' mark. The alteration can bemade from any of the representations, and thus any error detected in alater finishing step representation, can be corrected within thatrepresentation, before being altered for conformity in all otherrepresentations.

1. A computer-implemented method of printed document verificationcomprising: obtaining content data relating to the content of a documentto be printed; obtaining imposition data relating to at least oneimposition signature for the document; obtaining finishing datadescribing the application of one or more finishing operations to beperformed in order to produce the printed document; generating athree-dimensional parametric model of the document to be printed andfinished using the content data and geometric data obtained from theimposition and finishing data; and displaying a three-dimensionalelectronic output representation of the document to be printed andfinished based on the three-dimensional parametric model.
 2. Acomputer-implemented method of printed document verification accordingto claim 1, further comprising generating the at least one impositionsignature in accordance with the content data and the printing andfinishing apparatus to be used in generating the printed document.
 3. Acomputer-implemented method of printed document verification accordingto claim 1, wherein the imposition data describes a plurality ofimposition signatures, each imposition signature representing adifferent printed document section.
 4. A computer-implemented method ofprinted document verification according to claim 1, further comprisinggenerating an electronic imposition sheet representation, whichrepresents the content data as applied to the imposition data prior tothe application of the one or more finishing operations.
 5. Acomputer-implemented method of printed document verification accordingto claim 4, wherein the electronic output representation is generated byprocessing the electronic imposition sheet representation so as to applythe one or more finishing operations to the said imposition sheetrepresentation, in accordance with the finishing data.
 6. Acomputer-implemented method of printed document verification accordingto claim 1, wherein the method further comprises displaying theelectronic output representation.
 7. A computer-implemented method ofprinted document verification according to claim 6, wherein thegeneration of an electronic output representation further comprisesgenerating an animation representing the application of the one or morefinishing operations.
 8. A computer-implemented method of printeddocument verification according to claim 6, wherein the method furthercomprises applying an least one of texture and lighting effects to theelectronic output representation.
 9. (canceled)
 10. (canceled)
 11. Acomputer-implemented method of printed document verification accordingto claim 1, wherein, after the generation of the electronic outputrepresentation, the method further comprises interacting with theelectronic output representation.
 12. A computer-implemented method ofprinted document verification according to claim 11, further comprisinginteracting with the electronic output representation in one or more ofthe following ways: rotating a representation, opening pages in arepresentation, zooming into and out of a representation, or translatinga representation.
 13. A computer-implemented method of printed documentverification according to claim 11, wherein the interaction with theelectronic output representation is limited to interactions that wouldbe physically possible if the said printed document was producedaccording to the said one or more finishing operations.
 14. Acomputer-implemented method of printed document verification accordingto claim 11, wherein an operator is provided with a graphical userinterface to facilitate interaction with the electronic outputrepresentation.
 15. A computer-implemented method of printed documentverification according to claim 1, the method further comprisingdynamically editing the imposition data or finishing data after thegeneration of the output representation and re-generating the outputrepresentation based on the said edited data.
 16. A computer-implementedmethod of printed document verification according to claim 1, whereinthe one or more finishing operations comprise at least one of: creasing,cutting, embossing, gluing, perforating, strapping, stacking, folding,collecting, ganging, gathering, binding or trimming.
 17. Acomputer-implemented method of printed document verification accordingto claim 1, wherein the finishing data is obtained using additionalmanagement data obtained from a management information system.
 18. Acomputer-implemented method of printed document verification accordingto claim 1, wherein, when the finishing data describes a plurality offinishing operations, the method further comprises generating electronicoutput representations for each finishing operation.
 19. Acomputer-implemented method of printed document verification accordingto claim 18, wherein the plurality of electronic output representationsare generated in an order representative of the production of theprinted document.
 20. A computer program comprising computer programcode adapted to perform the steps of claim 1 when said program is usedon a computer.
 21. A computer program product comprising program code ona computer readable medium for performing the method of claim 1 whensaid program is run on a computer.
 22. A printed document verificationsystem comprising: an input device adapted to obtain content datarelating to the content of the printed document, imposition datarelating at least one imposition signature for the document, andfinishing data describing the application of one or more finishingoperations in order to produce the printed document; a representationsystem comprising a processor adapted to generate a three-dimensionalparametric model of the document to be printed and finished using theand geometric data obtained from the imposition and finishing data; anda display device adapted to display a three-dimensional electronicoutput representation of the document to be printed and finished basedon the three-dimensional parametric model.
 23. A printed documentverification system according to claim 22, wherein the input devicecomprises at least one of: a mouse, a tablet, a touch screen, a networkconnection, or a digital media reader.
 24. (canceled)